This report covers:
- In the past
- What is a choke?
- Shotgun chokes
- Chokes are more than a century old
- Lothar Walther chokes their barrels, too
- How to tell if you have a choke
- Back to 2022
- Diabolo pellets
- Pope
- Modern rifle barrels
- So — choke or not?
This past Tuesday in Part 5 of the Seneca Dragonfly Mark 2 report a reader named Bill, asked this question:
“BB,
Does the DF MK2 have a choked barrel?”
Bill
I answered him with this:
Bill,
“I don’t know. I rather doubt it because that is usually an extra step in the barrel-making process and has been shown to be of limited or no value when it comes to accuracy.”
BB
Then Bill came back and said
“BB,
I’ve been led to believe a choked barrel to be more accurate than non-choked
but I’ve only just started down this air gun path, so much to learn.
I assume there are probably no newly manufactured multi-pumps with a choked barrel?
I look forward to more of your findings on the Dragonfly Mk2, looks
very impressive so far.”
Bill
To which I responded:
Bill,
“I may have been one to lead you in that direction. I believe that a report on choked barrels is in order.”
BB
In the past
I don’t want to confuse you, but BB has written some things about choked barrels in the past that may not be completely accurate. That’s why I apologized to Bill. Remember, guys, I’m learning right along with you.
In June of 2005, just 4 months after this blog started, I said the following.
Some airgun chat forums are currently buzzing with discussions about choked rifle barrels and what they can or cannot do. As usual, there are a few knowledgeable people and a much larger crowd of kibitzers with nothing to say – and saying it very loudly.
What is a choke?
A choked barrel refers to a reduction in the bore dimensions at the muzzle of the gun. The purpose for this reduction, according to pellet makers at Handler & Naterman (H&N), is to size all pellets just before they leave the gun. It ensures uniformity.
Shotgun chokes
Shotgun barrels are choked to achieve different densities of shot at different distances from the muzzle. Today I’m just talking about rifle barrel chokes.
Rifle chokes are more than a century old
Let’s examine history to see if chokes really work. First we learn that Harry Pope, the acknowledged Stradavari of rifle barrel makers, almost always choked his barrels. Most of the guns he made (and ALL of the most accurate ones) were muzzleloaders, and you might wonder how a choked muzzle can benefit a bullet that is rammed through it during the loading process. Wouldn’t that squeeze it too small?
Well, when the powder charge ignites, burning gasses smack the base of the bullet hard, smashing it out fatter until it hugs every crevice of the bore. When it gets to the muzzle, the choke sizes it down once more just before it leaves the gun. Pope’s barrels set every world record in their day; a century later, they’re still regarded as some of the finest barrels ever made.
Lothar Walther chokes their barrels, too
A second endorsement comes from Lothar Walther, the German company that is well-known for making fine airgun barrels. They can supply their barrels with or without a choke, but their choked barrels out-shoot their unchoked barrels by a significant margin. They tell that to anyone who does business with them.
Now, a word from the school of hard knocks…
There are the incidents of hundreds of airgun tinkerers who have cut off the ends of their barrels for one reason or another. They nearly always suffer an accuracy loss that they can never recover. They will tell you the reason the shorter barrels don’t shoot as accurately is because of the new crown (the shape and uniformity of the muzzle), but the truth is that no amount of re-crowning will ever get those barrels to shoot again. The one instance where cutting off the end of a barrel improves accuracy is when the muzzle has been ruined by improper cleaning that has worn away the rifling.
How to tell if you have a choke
Use a cleaning rod to push a pellet through your barrel from the breech to the muzzle. You’ll feel resistance at about 1.5-inches to 2-inches from the muzzle on a deliberately choked barrel.
Pope lapped in his chokes during the polishing process. Modern barrel makers squeeze the bore down mechanically – a process known as swaging. On many springers, the act of swaging in the front sight dovetails on the outside of the barrel also reduces the bore at the muzzle. It isn’t a formal choke, per se, but it works just the same.
The choke discussion is a topic that has fueled conversations for more than a century, and it isn’t going to end here. An interesting book on the topic of accurate barrels is The Story of Pope’s Barrels by Ray M. Smith.
Back to 2022
Okay, over the 17 years this blog has been running, old BB has had occasion to learn a few things. Back in 2018 when I went to Sig to see the new ASP20 air rifle I asked them whether it had a choked barrel. Ed Schultz (yes, the same guy who is now back at Crosman) told me the ASP20 barrel was unchoked, and in their experience, it didn’t really need to be choked. When I shot it at Sig and again when I tested it for you in this blog I discovered he was right.
So — does a rifle barrel need to be choked? Sometimes yes, most times no. And get this — if it is an extremely well-made barrel by Harry Pope, it is choked and does need to be. And if it is an extremely cheap barrel from China, choking can help.
Let’s talk about China first. What does a choke do for a cheap barrel? It makes certain that the last part of the barrel to touch the pellet is uniform. If you have ever pushed a pellet through a cheap barrel with a cleaning rod you know there are loose spots and tight spots. A barrel like that doesn’t help accuracy very much. A choke can help a barrel like that.
But what if the barrel is uniform all the way through? Well, for starters, never get rid of that barrel, because it’s a special one. Then you say, “Aren’t all barrels supposed to be uniform all the way through?” Yes, they are supposed to be and no, they usually aren’t.
Diabolo pellets
But we shoot airguns and they have something in their favor that firearm bullets don’t have. They have soft thin skirts that get blown into the rifling when fired. Unless the barrel is really bad, that is a great plus that firearm barrels don’t have.
Pope
Harry Pope made barrels for lead bullets. There is a small bit of expansion at the bullet’s base when the powder goes off, but the barrel would have to be uniform all the way through for that to have the desired affect. Pope’s barrels were. Schalk’s barrels were. And a few other legendary barrel makers barrels were uniform all the way through. Pope simple hedged his bet by putting in about a half-thousandth choke at the muzzle end of the barrel.
Modern rifle barrels
How about modern firearm barrels? If they are made for shooting jacketed bullets I doubt you will ever see one that’s intentionally choked. Uniformity through things like barrel lapping is the preferred way of treating such barrels.
However, some .22 rimfire target rifles that shoot lead bullets are intentionally choked. Again, it’s the hedge against non-uniformity in the barrel. With lead bullets a choke will work.
So — choke or not?
This question is like asking which of your children do you love the most. If you have an answer you will never say it. Or you may want a choke just because you have heard they are good. Same, same either way.
I’ve always had better groups with a choked barrel, especially on lower powered rifles. So springers 17fpe and down.
BB,
So the best barrel is one that is uniform all the way through with properly sized pellets that will ride the rifling smoothly instead of rattling down the barrel before exiting? Now that answers why reaming the barrel blank before cutting the rifling makes a more accurate barrel.
Siraniko
Siraniko
Check out the FX smooth twist barrels.
Had a couple of their guns. They are accurate.
Tell me what you think about their design of the barrel.
Gunfun1,
FX smooth twist barrels seem to favor particular brand of pellets don’t they. Haven’t had the fortune to shoot one though. Their smooth bore followed by a gradual rifling seems to be an improvement on the Paradox rifling used in double barreled rifles. But in this case the relatively gentle handling of the pellet on initial acceleration followed by application of rotation by rifling seems to have helped establish their reputation for accuracy.
Siraniko
Siraniko
I tried different brand pellets in my FX Monsoons I had and they all shot good but the JSB. 22 caliber 15.89 pellets did the best. But yep the two FX guns I had where accurate.
Hi Guys,
This is endless discussion. I spoke to many people much further experienced than I am, which were the “insider blog tuners”. They did everything with airguns. So the experience is, you need to have a good crown on the muzzle to enable the pellet leaving the barrel free from potential side-air-flow effect. The choke has one advantage – it seals the pellet at the end of the barrel where, especially in springers, the air pressure may not be high enough to seal the skirt. Just to avoid the air going out somwhere from one side of the pellet first. It may cause some instabilities which will be more and more visible at the distance. Choke alone will not do the job if the crown is not properly finished. People who cut the choke and did a proper crown at the end of the barrel may not see big or any difference. We are talking good quality bore of course.
The mean sentence about the choke was that is a really good thing (with a proper crown) for the weaker springers. If you have a 12ft.lbs. or less springer, the pellet will accelerate mostly on the first 10inches of the barrel, then not any more (too less air). It means the pressure behind the pellet will decrease, depending on the cal. and barrel lenght it might be too less to seal the skirt at the end. There is a job for a choke to do at the end.
If you have a full power PCP there is no need to have a choke. This is always taking some energy away 🙂 But don’t worry, it takes very less amount of kinetic energy anyway. It is supposed to be only a small cal. change, not so dramatic as many describes (squeezing the hell out of the pellet) 🙂 🙂
BTW
I could not resist and I have tuned my new HW30s yesterday. My gosh is it lovely now! I gained a bit more power – now I have 7.5ft.lbs. I install a washer and rubber Oring below this washer, all under the spring. The shot cycle is just funtastic and there is no smell of dieseling anymore. Weihrauch put not too much grease inside but, unfortunatelly, there is some in the compression chamber and at the front of the piston seal. This is a lesson once again – dismantle ALL new springres and do the zero check, doesn’t matter which name is on it 🙂 Now I’m really happy. It is just amazing how smooth it is – and it is damn accurate. It has 395mm (11.51inch) barrel with a choke at the end. The crown is perfect, both do the job. In this case the pellet accelerates at approx. first 7inches only, then not anymore. So the pressure behind it at the end will not be big. The choke may help .)
tomek,
Do the sources that you sight mention the effect of choking on barrels shooting lead slugs. Slugs would be skirtless, so not as malleable as a diabolo pellet, and a slug would not get expanded upon firing, as BB describes for the black power rifle, since the pressure in even the most powerful PCP is much less than the smallest caliber powder gun. I just wondered if choking would have even less effect on solid lead slug/bullets for airguns.
Also, are these discussions and tunings international in nature or local to you?
Half
Halfstep – yes, according to my sources the slugs are in general not working good with choked barrel (mostly on the springers, below I explain another issue with low stabilization at low speed). It doesn’t mean it is always the fact. Full power PCP are usually without choke. To be honest I don’t have newest overview on that – the general discussion about choked barrel on the PCP layer does not exist as it was and still is about springers.
Many people tried to shoot slugs with springer airgun and what came out is that slugs need more stabilization (means rotation speed). Low power springer will not shoot slugs fast enough to make it accurate. High power PCP is a different story. Some guy measured .22 slug speed shooting chrony at 50yards. It still had almost 90% of the muzzle kinetic energy! So the BC is very good compared to normal pellet.
Additional information is that some slugs (and there are recently more and more many small manufacturers producing good slugs) depending on the alloy may cause the barrel to lost accuracy after 30 – 50 shots due to slug material covering strongly the rifling. It is confirmed. The barrel needs then to be clean with some effort.
Even more, the new PCP from Diana has also slug shooting option with optimized rifling shape barrel.
Look: https://www.diana-airguns.de/en/products/detail/diana-xr200-od-green
It definately has something to do with above mentioned issue.
The blogs and forum I sometimes explore are usually local but with the translator you might be able to catch the sense (to be honest it is not comfortable). One guy recently boought 4000lbs lead wire and build up a slug matrix, he delivers now local forum with slugs in .22 .25 and .30 cal. 😉
Tomek
I recently bought an HW30 myself. I find it to be very accurate and I would like to know if there’s something simple I could do without a spring vice in order to smooth some more the shots.
Also everyone;
I’m planning to ask my tuner to shorten the barrel of an Air King Diana 54 to 25cm, recrowning it.
Any thoughts on this?
Hi Bill,
Actually the HW30 is almost perfect as it is. What you can definately do is dismantle it, clean the original grease and put a new one. Not too much, not at all on the seal and into the compression chamber. The seal just make wet with silicone oil or special chamber oil and make sure the cylinder has some oil film before you will shot.
What I also did is:
– I polished the spring ends (it is not soo necessary but it makes it even more smooth to rotate)
– I polished the back of the piston (only for my good feeling actually),
– I put some bearing grease into the moving parts of the record trigger (is smoother now),
– Most important – my own patent, I put a washer below the spring and rubber Oring between the spring guide. This is a kind of impedance cut for the structure borne noise (vibration). The system is definately quieter after this action. At the end I gained some more energy (around 1 point something J) due to this washer and oring (more pre-tension).
I took some pictures fortunately (how man actions I did without making pictures… oh boy), please look:
HW30_mainspring_original.jpg
Original mainspring was just 6.2 inches long. Good prepared ends, like it should be. I was surprised that with this mainspring I get 7.6 ft.lbs. Nevertheless I always polish the ends with 1000 diamond polishing stone (fast and good enough).
Here is my patent which I try to apply always when doing first zero check:
HW30_Oring_washer_undermainspring.jpg
This time I did not have a proper washer so I made one using a spring washer which I put back with some force and polished the edges. It will do. Perhaps this picture does not show exactly what is meant, I found another one (different system):
OringbelowMainspring.JPG
Actually I have it in three different springers installed. Please make sure the Oring is tight enough, so when it will be squeezed it stay in place and not go outside (just need to check it before installation).
Of course you can buy some tuning kit. The difference would be the mainspring (in my opinion 8ft.lbs is MAX for this system to keep it smooth) and its guiding. It would be perhaps good also to install the mainspring guide in the piston (as a small hat). But – it is not so necessary.
At the end the muzzle pellet velocity delta is not much better than it was out of the box. I get something like average 672fps plus minus 4 fps. I think this is a very good value. The difference is that the system is quieter, smooth without spring buzzling after shot and – it is not dieseling at all. This was the main reason to do the zero check and dismantle it.
The mainspring pre-tension was so small, that I was able to dismantle and put the system back by myself alone. Really no big deal! It is so user friendly made! 🙂
Tomek
Thank you very much for your response. I really appreciate it.
If only you could give me your opinion on my second question. There is this Diana 54 T01 for which I bought a PG4 kit. I would like to shorten the barrel to 25cm along with the kit installation. What do you think?
Thanks a lot in advance.
Hi Bill sorry I forgot to answer the second question.
At the time point where I went deep to HW50 full custom tuning I had a lot discussion with experienced tuners on this topic – how to shorten the barrel.
The AirKing has a pretty large compression chamber, the air volume is relative big. It means with a full power or just high power mainspring it will accelerate the pellet on a longer way than low energy springer. The experiments conducted showed that for a 12ft.lbs. springer in .177cal 28cm is always optimal lenght. It means with longer barrel there is no energy win anymore.
In your case: if you have .177 cal you need not less then 33cm. In .22 cal I would still cut at 30cm to ensure you will not lose kinetic energy. 25cm seems to be borderline in this case.
I can assure you will see the difference in the accuracy. The shot cycle will be shorter as the pellet leaves the barrel faster. It seems to be only a very little time difference, but I was surprised how much better I can group with 28cm vs. 39.5cm barrel lenght. It is like beeing surprised at each shot.
Please check if you have choked barrel. If yes, then it would be wise to take the barrel out of the system, cut it at the rear side and adapt to the system again – without removing the choke and crowning (which I assume is very good). I did it with my HW50, there is a different story behind it (smooth bore, not rifled but scratched… I described it a bit in some HW50 blog part).
I hope I could help. In general – more barrel lenght is always good with PCP (of course in a logic range), the springers are different (air amount, air discharge after it was compressed and hot which makes it colder fast again and the pressure goes down even faster).
Barrel which is 50cm or more I would definately cut directly in a springer, perhaps not if the cocking effort would be too much 🙂
One more observation – the shot noise will be much louder with shortened barrel. You will see how the bigger air pressure by discharging in shortened barrel makes the big difference. And one more advantage – the pellet skirt is much better sealed with shortened barrel at the end 🙂
Thank you very much for your reply to my second question also. I understand that I can shorten the barrel length down 10cm, to 32-33cm without energy loss. As far as it concerns the noise, I already have a silencer for this one. The good things of living in Europe…
With your help it seems that the project is on.
Thanks a lot once more.
Bill – I’m glad about your progress. It is always a hard decision to make. You will be satisfied at the end – and a short barrel with silencer looks really good.
With a full power powerplant and .177 cal. I would not go below 30cm lenght, this would be the treshold value.
The answer to this question is 42.
So where did we land on this?
Derrick
I think we are down to “Maybe,, maybe not”.
Ed
Vana2 knows.
LOL!
This discussion should be framed in the form of Vogon poetry. “To choke or not to choke…who shall choke the chokers?” Better stop before someone chokes FM. Understandably.
Good post, but I agree with RidgeRunner – and not just as a joke, but as a “logical proposition” . . . “42” was the answer, but nobody really knew what the question was (lookup Hitchhikers Guide to the Galaxy if you don’t know what this is in reference to).
To us purchasers and shooters, the answer comes from the barrel itself. It either has a choke or not, and it either shoots well or not. To us individual gun users, that’s all we get to know. Changing an existing barrel is often a hit or miss proposition (as discussed in the post) so that is it for us. But manufacturers get to know more data – like Sig and LW discussed in the post. They get to know the statistical results based on testing and feedback on their products.
I think the purpose matters – like Edw said, I see better results with the choked barrels in most pellet applications. But I do think it makes sense for a company like Sig to “know” that for a particular gun application (like the ASP20) that an unchoked barrel might be best, and for LW to “know” that for pellets in general the choked barrel is better, but for slugs the unchjoked might be better. I have dabbled with slugs, but with the exception of the small sized FX Hybrid slugs, I don’t find my accurate choked barrels to do well with them (but I have not slugged those barrels – I have just been trying different head sizes out in them).
I think there is likely a big difference in results with chokes in airguns between slugs and pellets, given the energies involved in the powerplants (compared to PBs) and the energy needed to force a slug through a choke. I have messed around with this with my Huben, as it came with an unchoked barrel that shot slugs great but pellets not so great – and since I prefer to shoot pellets, I bought an LW choked barrel for it (the came with those back in 2018, and people changed them out to shoot slugs better) and it shoots pellets well, but not so much the slugs now. So this could be an area of other exploration, as it aligns with the “common knowledge” discussed on many blogs about shooting slugs. It seems that to optimize a gun for pellets vs. slugs likely does take a different barrel.
Alan,
I’m just starting to dabble with slugs as well. It’s a curiosity thing as I’m perfectly happy shooting pellets.
Guessing here without knowing. I suspect that pellets are OK with chokes because (being waisted) they only have two small contact points (head and skirt) with the bore and can easily tolerate being compressed a bit. Slugs on the other hand, are solid cylinders that would have to increase in length as their diameter was decreased by the choke. I expect that extruding them through the choke is bad for accuracy.
While I’m speculating, I think that off axis loading (because of the shape) of slugs is the cause of poor groups.
Hoping to do some experimenting next spring.
Hank
Hank,
I just posed a question to tomek, above, on this subject.
Half
Thanks for the heads-up Half!
Hank,
I answered Halfstep above. Slug which is heavier and usually much longer then a standard pellet need more stabilization (high rotation rpm). To make it accurate you need more velocity at the muzzle or “faster rifling” of the barrel. So with the standard barrel some guys came to the conclusion that generaly slugs need speed. Only high power PCP are really good to shoot slugs. Experiments with springers were done without big success. Weaker springer might event not shoot the slug out of the barrel. The strongest springers are too weak to shoot slugs fast enough (more friction in the barrel, more moving mass – both needs more air to accelerate).
You can buy good slugs from H&N. Like this 30grain .22:
https://www.versandhaus-schneider.de/product_info.php/cPath/40_95_157_1331_1979/products_id/40974
To be honest I tried only the rabit magnum power “kinda slug”:
https://www.versandhaus-schneider.de/product_info.php/cPath/40_95_157_1331_1979/products_id/33569
It was pretty good. Needs air behind it. Nothing for the springer.
There are known issues with standard rifled barrel regarding some slugs leaving too much material on the rifling causing issues with accuracy. You need to consider cleaning the barrel often when shooting slugs.
tomek,
Thanks for the reply and the links!
Agreed, if you are talking slugs you are talking PCPs. I bought an Impact MK2 (.22 cal, with 700 mm pellet and slug barrels) as my long-range airgun and slug testing platform. The Impact (easily) has the power needed and its tuneability is well suited for testing.
I’ve learned the gun (shooting and tuning) with 18 grain pellets and am just going through the same process with 25 grain pellets so I
can extend my range and experience.
Since long range (target) accuracy is the goal, power is not a concern and I’m planning to test slugs in the 20 to 30 grain weights.
Hopefully I can find a tune that favors the JSB Monster Redesign pellets and the JSB KnockOut slugs to have an either/or option for ammunition. If not I’ll experiment with various slugs then retune for pellets.
For me, slugs are an interesting development in the airgun world and I’m curious about them – mostly because of the tuning challenges they provide. The whole advantage of slugs is their excellent BC and long range – which I view as a big disadvantage LOL! The sub 80 yard ranges I shoot at are well within the maximum effective range of pellets so I prefer them.
IMHO, for my applications, pellets are a much better choice. They are less expensive, more readily available, more accurate, required less HPA and their shorter range makes them safer to shoot in my area.
I’m not knocking slugs, think they have a lot of potential for the people pesting pigeons and ground squirrels at long ranges but my interests are not in that direction.
Still, slugs will be fun to experiment with and I expect that a tin of them will keep me entertained for hours ( … hmmmm, maybe that is why my wife is encouraging me to try them 🙂 )
Thanks tomek! I like technical discussions and am enjoying your posts!
Cheers!
Hank
Hank, the pleasure is mine! I like also to talk about the deep details 🙂
Actually I think it is going to be a natural developement with slugs in the airgun world. It is slowly clear for all that this ammo makes sense only in PCP powerplant with “the more power is better” tendency. Suddenly H&N, JSB came up with high quality slugs, mostly designed for hunting.
What I would like to check definately is Rabbit Magnum Power .22 with 25grain at it’s best (910 – 980 fps). It seems to be potential a very good combination of slug-pellet-like compromise. What I mean is the reports from guys who are making slugs and testing them. The big issue is sometimes the projectile guidance in the barrel. The most fireram design for supersonic projectile will not work properly in the airgun world of subsonic speed. The guidance of the projectile head might be the key.
————————————
You motivated me – I just came downstairs and shot one Rabbit Mag .22 copper for you to show you what I mean. The picture is not the best – sorry for this, no time to pick up the real camera, it is enough to show what I mean:
HNRabbitMag_22.jpg
Look, you have a very good guidance of the head. Many slugs like a “normal” bullet have contact to the barrel only at the back. I saw many reports about issues with it. Sometimes they are not comming straight out but already a bit off-line. This makes them to turn around in all axis, especially after a longer distance.
Now I’m curious and perhaps I will buy this light and heavy H&N hollow point slugs (which are a bit like just described) to see what happend. My issue is I don’t have a PCP powerplant to really shoot them. I mean 26ft.lbs. is not enough to really test it.
If you are going to test some slugs please tell us about your results.
I’m pretty sure that this ammo will dethrone normal pellets in high power PCP class, long range shooting, very soon.
AlanMcD
I just posed a question to tomek, above, on this subject.
Half
Alan,
Even the famed FX has brought out barrel liners optimized for slugs.
BB
So Pope’s barrels were uniform all the way through but hedged his bet by choking. This says at least to me that Pope believed choking was preferred over not choking for best accuracy using lead bullets. This suggests that accuracy using lead pellets rarely if ever suffers when the barrel is properly choked and crowned.
Seems to me that accuracy with a uniform but unchoked barrel may be as accurate but won’t be more accurate in a springer and maybe even a PCP.
Deck
Deck,
And then we have the Avenger which has neither choke nor crown. Hmm…
RR
Guessing a few folks cut their barrels to shorter length and got better accuracy.
Deck
Deck,
It is a hit or miss kind of thing. It either works or does not. Nova Vista figured out how to do it. It is the kind of experiment that if you cannot afford a new barrel, it is not a good idea to try.
Many manufacturers will do a bit of research to optimize production cost, if for no other reason. Many just buy LW barrels and be done with it. By the way, you can get unchoked LW barrels.
Why not shorten it from the breech end?
RR
“Why not shorten it from the breech end?” Customizing Mausers into sporting rifles has me thinking inside the box. Sometmes that went well. Other times not. A hundred years ago my dad ruined his accurate star gage 03 Springfield by letting a gun smith shorten the barrel to make a beautiful shorter. It sprayed bullets every whichaway.
Deck
As you have pointed out, shortening a barrel can have a negative effect. Did your Dad try different “loads”? With a shorter barrel he would need a faster burning powder, maybe even less of a load. That would have kicked off a round of experimentation.
RR
I wish I could answer your question. Dad passed away 40 years ago which is about the time I got into reloading. He believed barrel flexing was the problem. Dad didn’t reload but his brother for sure did. His brother later was a ballistics expert at Aberdeen. I can only guess that his brother was involved in testing this rifle. Dad lost interest and put it away in the attic. Eventually it was stolen likely by painters. I have often wished I had it.
Deck
“…the truth is that no amount of re-crowning will ever get those barrels to shoot again.”
B.B.,
Did you mean that if some hacker (like me =>) cut the choke off his barrel, it will never shoot well again because my “crowning” would be as sad as the hacksaw cut?
Or did you mean that even if a good machinist used a lathe to cut and re-crown his barrel that, unless he was super-lucky enough to have a Pope-type totally uniform barrel, if the end of the barrel is now on one of those loose spots, even re-crowning won’t help as the pellet will now not be making uniform contact with the crowning since it got squished down in one of the tight spots?
Sorry if that sounds like a rambly question…too little caffeine today! 🙂
Take care & God bless,
dave
Caffeinated Dave,
Remember what I said in the beginning?
“In the past
I don’t want to confuse you, but BB has written some things about choked barrels in the past that may not be completely accurate. That’s why I apologized to Bill. Remember, guys, I’m learning right along with you.”
BB
“In the past…Back to 2022”
B.B.,
My apologies! Un-Caffeinated Dave did not have his brain firing on all cylinders this morning!
Fully-Caffeinated Dave sees your point, and withdraws the question he never would have typed had he only been properly caffeinated in the first place. LOL! 🙂
Blessings to you,
dave
There is no place for “I believe” here. The most of the tests you can find are usually not have the continuity of functions at all. It simply means there are not many real scientific made test like a test should be conducted to compare A to B.
What is clear for me so far:
1. We are talking about good bore barrels only to compare.
2. Good crowning and choke will help more in a moderate / low energy powerplant. As the air pressure behind the pellet is low at the end of the barrel the choke may additionally seal it shortly before leaving. It makes the air flow constant without any bad side-kick effect on the pellet shortly before and directly after leaving the barrel.
3. Choked barrel will have less sense with increased energy of the airgun powerplant. If the air amount to barrel volume ratio will tend to keep the air pressure high shortly before leaving the barrel the proper crowning is the most important thing.
These are the basics in my opinion and based on this each test to compare choke / no choke makes more or less sense. Ideally it would be to compare the same cal. barrel lenght for low / medium and high energy airgun powerplant, shooting only from the benchrest without any wind influence, with controlled V0 of the pellet. And you need at least three choked and three non choked barrels with same crowning technique for a statement at the end.
What people do is compare different barrels combined with different airguns etc. And then of course nothing makes sense at the end – this guy had a barrel A and cut the choke without a proper crowning it on the 14ft.lbs. springer, the other guy did something to his 40ft.lbs. PCP barrel… heelloouuu.
There is a reason why choked barrels are made for some airguns. It is not cheaper to make it – nobody will just do it without a purpose and pay additional cost for nothing. Nowadays it is not common to do something because “we always did it” and pay for it, without any evidence it makes sense 🙂
tomek,
I believe you would enjoy the book, “The Bullet’s Flight — From Powder to Target” by F W Mann. Mann took his journal of 37 years of experimentation and concluded that it is impossible to know if a rifle barrel will be accurate without shooting it. He spent what would today be several million dollars buying numerous custom Pope barrels and other equipment for his experiments.
BB
BB
Thank you I will look for this book!
So … it means we can put this whole theory behind it in to the trash 🙂 (?) But honestly, I think there is a way to determine if and when it really makes sense to choke the barrel.
Why many of Lothar Walther barrels are choked? Why Weihrauch still do choke it in the springers? Just a tradition?
tomek ,
May I say that I don’t know? Because I don’t.
BB
BB
Things are getting complicated again…
The “why” behind how products are made can have many different answers.
Sometimes it’s the cheapest option.
Sometimes it gives the best result.
Sometimes it’s a combination of the first two.
Sometimes it’s more expensive, doesn’t improve the function at all, may even make it worse, BUT for some reason people want it anyway so the manufacturer gives them what they want.
Between the 70’s-80’s offroad motorcycles went from having two rear shock absorbers to just having one. At the time Husqvarna got the best performance using two Öhlins shocks on their motocross bikes, but they went to single shock anyway – if they had kept the old design no one would buy the bikes because of the “outdated” construction.
Anyway. Not having access to all the background facts makes it hard to figure out why anyone makes anything in a specific way.
G-son,
“Anyway. Not having access to all the background facts makes it hard to figure out why anyone makes anything in a specific way.”
Totally agree! Thank you for this post, I forget about these facts sometimes. Without the background information I often thin too much, perhaps the water is not so deep at all…
B.B. and Readership,
“The answer to this question is 42.” RidgeRunner is correct!
I have done a great deal of study on the THEORETICAL math of Internal Ballistics and it IS UGLY. Ugly because every barrel, projectile, and powerplant IS different; not to even get into the ever changing external environmental conditions that always mess with results.
Personally I don’t think much of the CROWN theories! WHY? Because the crown is actually one of few the Constants among all too many variables; granted you need to start off with an acceptable crown. Testing Internal Ballistics is a young Art in the world of smallbore projectile throwers. Most of Pope’s work was based on carefully observing external results and drawing interesting inferences on what about a barrel was causing them. If you do any powder reloading you know what his biggest devil was!
Inmy opinion based on experience and some amount of study on Internal Ballistics chokes have a place in Scatterguns and in barrels that are not precision manufactured to best standards. The rest is mostly Marketing Gimmick.
The answer to this question is 42!
shootski
PS: Please! NO choking, especially rifled, Big Bores.
Shootski
Time to regroup.
You got some explain’n to do.
Crowns and chokes.
I hope you can give some explanations of what you mean.
Gunfun1,
Crowns: IF it is acceptable then what is the question. If you have excessive air pressure then the projectile will still be accelerating away from the muzzle and the Mass of the projectile is so much greater than the propellant gas molecules that by the laws of inertia and being adiabatically cooled the molecules slow VERY promptly immediately out of the barrel. This is only true for non burning propellant.
Chokes: On rifled barrel bores that are uniform in inside diameter, have acceptable Leade/Chambers, and the proper size projectile don’t need a choke to swage them into submission. For that matter to reorient it to the bore axis.
There is so much more important STUFF to worry about getting right first…barrel harmonics being the biggest in my opinion. Harmonics are actually the last thing that is a variable that the projectile experiences before transitioning to External Ballistics. Just one thing, among many, to think about is that the projectile doesn’t escape the muzzle all at once! What is the wave plot at the projectile tip…midpoint, and tail? Obviously the point(s) of projectile contact come into play. The center of Mass, the aerodynamic Center of Pressure, and the complexities (gyroscopic) of the spin.
Sorry that was more than one. Enough to give a shooter a headache!
Folks make a handsome living throwing around Internal Ballistics theories and modeling those theories.
shootski
Shootski – 🙂 Thank you. The theory may be complicated up to sky is the limit. I personally suffer from going as deep as possible in every theory I think is important to understand something. Somewhere you might get lost – and then I remember to talk to the most pragmatic people you can talk with: THE AIRGUN TUNERS! 🙂
They told me what I already shared in this blog – good barrel and perfect crowning is the key, the choke can help on the weaker springer (or limited PCP) due to this “seal the pellet at the end of the barrel” issue. I talked to guy who is tuning every day, it has become his full time job and passion. He also told me, sometimes everything should be perfect and is not accurate, there are some cheap barrels which are deadly accurate… hehehehehe 🙂 it would be so easy if the theory would follow the reality – or opposite around 😀
Shootski
Of course there is variables. But from what I have experienced is crowning of the muzzle does make a difference. You know it when you get the crown right. And you know it when it’s wrong.
And in the past I have pushed pellets half way down the barrel and back out the way it went in. Then pushed pellets all the way through and measured both pellets to confirm if a barrel was choked our not. If I shot the same brand pellet (JSB) in a unchoked barrel then a choked barrel. The choked barrel always was more accurate. And that was with rifled barrels and smooth bores.
And yes if I found the right fit pellet the uncooked barrel would get accurate.
So as it goes. Variables.
BB,
I just ran across a spring piston pistol that I didn’t know even existed and wondered if you had plans to review it? It’s the Umarex Ruger Mark IV pellet pistol. It looks to be made around the Browning Buckmark design by Umarex. My Buckmarks are great guns and I think I bought them on your recommendation. If you get your hands on the Mark IV I’d like to hear your take on it.
Half
Half,
It looks good. I have been wanting to test it.
BB
BB,
Will you have a Ruger .22lr to compare it to?
Half
Half,
I do have a Ruger Mark II Target.
BB
I know I’ve not done a ‘real’ scientific test…but at 10m my Slavia 630 (unchoked) is just as accurate at my Avanti 853c (Lothar Walter choked).
I have to agree with B.B., if you have a quality barrel the difference is going to minuscule.
CBS
Read my comment a couple of posts obove to Shootski I just wrote about crowns and chokes.
ROTFWL!
There are airguns out there that do not have chokes OR crowns.
There are cheap airguns that are very accurate and not pellet picky and there are expensive airguns that are very pellet picky and really not that accurate with the RIGHT pellet.
It has been demonstrated repeatedly that two identical airguns are not.
Factors such as harmonics, metalurgy, caliber, velocity, type of rifling, twist rate, yadayadyada also have to be considered.
As I understand it, choking is to reduce the size variable of projectiles. With more and more pellet manufacturers paying attention to such variables, it is less pertinent.
Give some thought to what is going on to time and again hit a target the size of a dime at 50 yards.
There are too many variables that many do not even know about. Do not overthink it. Just do it.
The answer is 42. 😉